A color filter is a key component for a liquid crystal display to enable colorizing. The process for preparing a color filter comprises forming a black matrix on a substrate, coating a photoresist onto the substrate having the black matrix formed thereon, and subjecting the photoresist to pre-baking, masking, and exposure, whereby the exposed photoresist will undergo a cross-linking reaction such that it is remained in a subsequent alkaline developing process, and the remained pattern will be cleansed, developed and hard-baked at a high temperature, to produce the color filter.
During the process of producing the black matrix and the filter layer, the edge portion of the filter layer connects to the black matrix at a certain gradient to avoid light leak. Because most of the photoresists exhibit a high rigidity after high-temperature hard baking, the resulting filter layer is not liable to bend and sink to form a gradient. This results in a steep angle of slope occurring in the connections between the black matrix and the filter layer, which would easily cause light leak. The embodiments of the present invention aim to provide a photoresist having a compact and smooth surface and a gradual angle of slope.